Spatially Resolved, Multiphase Mass Outflows of the Seyfert 1 Galaxy NGC 3227

TL;DR

This study delivers spatially resolved, multiphase mass outflow profiles for NGC 3227, integrating ionized, warm molecular, and cold molecular gas measurements with Cloudy photoionization models to trace gas evacuation from the inner few hundred parsecs. The ionized phase dominates the instantaneous mass outflow rate (peaking near $ uildrel ext elax ext rac{19.9}{9.2} m \,M_igodot yr^{-1}$ at about $47\rm \,pc$), while cold molecular gas also contributes substantially (up to ~$23.1 \, M_igodot yr^{-1}$ at ~57 pc) and warm molecular gas remains small in comparison (∼$10^{-3}$–$10^{-4} \, M_igodot yr^{-1}$). The combined, azimuthally averaged outflow rate peaks at ~ $37.9 \, M_igodot yr^{-1}$ around $54$ pc, with evacuation timescales for the cold molecular reservoir spanning $10^{6.0}-10^{7.6}$ years, suggesting AGN-driven clearing can regulate the inner gas content on timescales comparable to the AGN duty cycle ($10^{5}-10^{8}$ years). These results emphasize the importance of resolving multiple gas phases to understand feedback efficiency and the connection between nuclear winds and galaxy evolution. Overall, the study shows that AGN feedback in NGC 3227 is capable of rapidly depleting central gas reservoirs and potentially modulating future accretion and star formation in the host galaxy.

Abstract

We present spatially resolved mass outflow rates of the ionized and molecular gas in the narrow line region of the Seyfert 1 galaxy NGC 3227. Using long-slit spectroscopy and [O III] imaging from from Hubble Space Telescope's Space Telescope Imaging Spectrograph and Apache Point Observatory's Kitt Peak Ohio State Multi-Object Spectrograph, in conjunction with Cloudy photoionization models and emission line diagnostics, we find a peak ionized mass outflow rate of $\dot M_{\text{ion}} =$ $19.9\pm9.2$ M$_\odot$ yr$^{-1}$ at a distance of $47\pm6$ pc from the supermassive black hole (SMBH). Using archival data from the Gemini-North Near-infrared Field Spectrograph measuring H$_2$ $\lambda2.1218$ $μ$m emission, we find a maximum peak warm molecular outflow rate of $\dot M_{\mathrm{H_2}} \le 9 \times 10^{-4}$ M$_\odot$ yr$^{-1}$ at a distance of $36\pm6$ pc from the SMBH. Using archival data from the Atacama Large Millimeter/submillimeter Array measuring CO(2-1) emission, we find a maximum peak cold molecular gas mass outflow rate of $\dot M_{\mathrm{CO}} \le$ $23.1$ M$_\odot$ year$^{-1}$ at a distance of $57\pm6$ pc from the SMBH. For the first time, we calculate spatially resolved gas evacuation timescales for the cold molecular gas reservoirs ostensibly sourcing the outflows, and find that evacuating gas to $\sim$400 pc from the SMBH occurs on timescales of $10^{6.0} - 10^{7.6}$ years. These results indicate that the multi-phase AGN outflows are effective in clearing the inner few hundred parsecs of NGC 3227's gas content on timescales that may set the AGN duty cycle of $10^5 - 10^8$ years.

Figures (11)

• Figure 1: Optical image of NGC 3227 (left of center) and NGC 3226 (above center) taken by the Sloan Digital Sky Survey with ugriz filters. The inset shows a color-composite image of the inner region surrounding NGC 3227's AGN, where red colors are from the HST WFC3/UVIS F658N filter, green colors are from the HST WFC3/UVIS F547M filter, and blue colors show F550M and F330W filters from Hubble's Advanced Camera for Surveys High Resolution Channel. Image credit: NASA / ESA / Judy Schmidt.
• Figure 2: Multiphase flux maps of the central regions in NGC 3227. In each map, north is up and east is to the left, and the white star marks the position of the SMBH. (a) A map of the ALMA CO(2-1) flux density, originally shown in alonso19. (b) A map of the NIFS H$_2$$\lambda2.1218$$\mu$m emission. (c) A map of a continuum-subtracted HST WFC3 F502N image of the nucleus, which shows the small-scale structure of the [O III] $\lambda5007$ emission. The heavy cyan lines represent the outline of the KOSMOS slit oriented along the galactic minor axis, which we use in our analysis. The light solid lines represent the KOSMOS slits oriented along the galactic major (PA = 150) and outflow (PA = 190) axes. In all three plots, the maps are overlaid with annuli that we describe in Section \ref{['sec: annuli']} and contours that better reveal the morphology of the flux distributions.
• Figure 3: BPT ionization diagrams for APO KOSMOS observations along the minor (PA = 240$^\circ$) axis. Positive distance refers to the north.
• Figure 4: (a) The observed [O III] $\lambda$5007/H$\beta$$\lambda$4861 ratio as a function of distance along the kinematic minor axis, which has been corrected for projection effects. The shaded region represents the uncertainty in the observed line ratio. (b) The predicted [O III] $\lambda$5007/H$\beta$ ratio (curves) as a function of $U$ and $n_\mathrm{H}$ from a grid of Cloudy models. The point on each curve represents the $U$ and $n_\mathrm{H}$ that also satisfy Equation \ref{['eq: U_nH']} at a given distance (in this example, we chose 134 or 154 pc). The point that best matches the observed [O III]/H$\beta$ ratio at this distance (dotted line) is selected as the correct $U$ and $n_{\text{H}}$ for this location. In practice, we use a finer grid of $U$ and $n_{\text{H}}$, only showing three curves here for illustrative purposes. (c) log($U$) (red, solid line) and log($n_\mathrm{H}$) (blue, dashed line) as functions of distance along the slit, where the shaded regions represent their respective uncertainties.
• Figure 5: The velocity laws for the ALMA CO(2-1) (blue solid line), NIFS H$_2$$\lambda2.1218$$\mu$m (red dot-dashed line), and HST [O III] $\lambda 5007$ (gold dashed line) data that are used to calculate the maximum mass outflow rates for the cold molecular and warm molecular gas, and the approximate mass outflow rate for the ionized gas.